The present invention relates to engine monitoring and more particularly to monitoring of gas turbine engines utilised with respect to aircraft propulsion.
It is important with respect to engine operation and particularly with regard to gas turbine engine operation to monitor various component parts of the exhaust gases from the engine. These component parts generally indicate the efficiency with respect to engine operation and ensure that engine operation remains within acceptable environmental and regulatory authority limits. It will be appreciated that engine monitoring can be performed either continuously or during engine set up or during a calibration stage. Ideally, engine monitoring should be continuous but it will be understood particularly with regard to gas turbine engines operated with respect to aircraft propulsion that the additional weight of monitoring equipment and also space constraints limit the possibility with respect to continuous engine monitoring.
Currently, exhaust emissions measurements are carried out by sampling exhaust gas with probes or rakes mounted behind an engine on a test bed. The samples taken are transferred to a number of measuring instruments outside of the test bed presentation of the engine. Clearly, such an approach does not lend itself to ongoing engine monitoring and furthermore the transfer of the samples taken from the test bed presentation of the engine may alter the results provided.
In the above circumstances, non intrusive analytical techniques for monitoring engine exhaust emissions are being devised or utilised with respect to engine test bed operations. These non intrusive approaches incorporate use of spectroscopic and laser induced incandescence in the exhaust plume such that the emitted infra red and incandescence can be measured by an appropriate spectrometer. Packaging such non intrusive systems into an engine requires great care to avoid excessive weight and for space utilisation.